Archive for the ‘Backend’ Category

It was in the dark ages of the Reagan era when I logged my first encounter with the File Transfer Protocol. I was involved in some nefarious video game-trading ring of the innocently naive variety, and a friend of mine had that hot new copy of Vladivostok Putting Challenge that I wanted oh so badly. The only problem was that he lived all the way on the other side of Orange County. Being too young to drive, neither of us had access to a car, and snail mail was just too darned slow. I wanted to lay down sloping fifteen-footers and rub it in the face of the Reds today, not in a week. “No problem,” my friend assured me. “Just log in to my server and grab it with FTP.”

“FTP? What is that?” I asked. My friend let out an Oscar-worthy sigh and gave me the quick run down of the Internet protocol that would forever transform my life.

Last I heard, my friend is collecting Galaxie 500s in Michigan, so calling him up with your FTP questions isn’t really an option anymore. Lucky for you, I’m here to give you a holier-than-thou sigh of my own and send you down the dharma path. For those of you who are entirely new to this whole game, we’ll start with a basic primer on the most comely of acronyms.

A picture’s worth a thousand words. An old saying, but true enough on the web where you can transfer chapters of text in the time it takes to download just one big image. Ever notice how pictures are always the last thing to show up when you’re surfing? That’s because the biggest hunk of download time comes from the image files.

Over the next four days, we’ll be looking at all the different ways to get pages down to their leanest and meanest. Today we start with the most egregious and most obvious culprit: images.

By the way, a lot has changed since the first edition of this tutorial – there’s more to optimizing image performance today than just knowing your GIFs from your JPEGs. (Though we’ll review that, since this may be your first time around.) There are now other file formats (like PNG) worth considering, and improved weighted-optimization techniques to throw into the mix.

And, hey, quite a bit hasn’t changed. For one, web users haven’t gotten any more patient. It doesn’t matter how ice-cool your images may look – if they can’t be downloaded quickly over a 56K modem, very few people without broadband will stick around to see them.

Fortunately, there’s still a host of tricks and optimizations that web designers can implement to speed image downloads. Let’s start with the easiest thing in the world.

Hey, you! What are you doing? Where are you going? More importantly, what are you clicking on?

If only it were that easy. But no, most users like to travel the web incognito. They come to your site, poke around a few files, download a PDF or two, and then — poof — disappear, leaving nothing but questions in their wake:Where did they come from? Which browsers are they using? Are they experiencing any errors?

The most thorough method of tracking users is by planting cookies, which some folks consider rude or invasive, and, oh yeah, you need to know how to program them. Not to worry — there is an option that requires very little technical know-how, comes at no (or nominal) cost, and may already be a part of your site’s backend. I’m talking about logs!

On the resume that convinced Wired to hire me, I said that I knew enough about Unix that it didn’t scare me anymore. This wasn’t exactly true. Unix was still a chilling concept for me when I arrived at the San Francisco office armed with a copy of Unix for Dummies. The managing editor steered me to my desk and instead of the Macintosh I was hoping for, there sat a purple SGI machine.

I realized then that I needed to learn a lot about Unix fast. Initially I tried using SGI’s graphical user interface, which mimicked the Macintosh desktop fairly well, but soon realized that it was just too damn slow. So I stole some better Unix books from the engineering staff and found a nice Unix expert to help me. Soon I was cp-ing, mv-ing, and chmod-ing like lightning. Unix still gives me the occasional nightmare, but basically I love it. It’s fast, it makes sense (most of the time), and anyone can figure it out with a little work. Plus, it looks great on a résumé. If you can convince a prospective employer that you have a working knowledge of Unix, you’re one step ahead of everyone else who is too scared even to try figuring it out.

I’ve put together a very basic explanation of Unix to get you started. But first, a warning. Unix is very powerful. The wrong collection of keystrokes can blow away files that you’ll probably never be able to recover, so practice on sample files before you move on to anything important.

Go outside and pop the hood of your car. You should see a thick metal barrier at the back of the engine compartment. This is called the firewall. To see how it works, poke a small hole in the fuel line so that a tiny amount of gasoline starts dripping on the engine block. Now close the hood, start the car, and head out on the highway (Some of you may choose to save life and limb (and time!) by merely visualizing this exercise).

If you have positioned the puncture correctly, within a few minutes the escaped gasoline should ignite and cause a small engine fire. At this point you may see smoke emerge from the engine compartment. Continue driving. You should be able to proceed a considerable distance before the heat becomes uncomfortable and toxic fumes and flames start to enter the passenger compartment.

The reason you can drive so far with a flaming engine is because the firewall is a highly effective barrier between the engine compartment and the passenger compartment. If your car had no firewall, the engine fire would have already melted the dashboard electronics and plastic, destroyed the upholstery, and toasted you to a crisp.

Now. Pull over and very carefully extinguish the fire.

A similar principle can be applied to networked computers. Picture your machine as the cozy, tricked-out interior of your automobile, and the outside world as the dirty but powerful engine that makes it go. It won’t do to have the vulnerable components of your network exposed to the engine’s maliciously raging heat — it’s best to install a firewall.

Let us abandon our weakening metaphor here before it carries us into a ping-pong tournament without a paddle. A firewall, in the networking sense, is a machine that straddles the interface between a private network and the Internet at large, and follows predetermined rules for allowing certain traffic to pass, while blocking traffic that’s unwanted.

So, how to get yourself one of those disaster-averting firewalls? You can start by reading on.